The present technology relates to a wiring substrate, a method of manufacturing a wiring substrate, a component-embedded glass substrate, and a method of manufacturing a component-embedded glass substrate, and more particularly to a wiring substrate, a method of manufacturing a wiring substrate, a component-embedded glass substrate, and a method of manufacturing a component-embedded glass substrate, which make it possible to suppress characteristic variation of an active element provided on the wiring substrate.
A glass wiring substrate on an entire surface of which an active element such as a TFT (Thin Film Transistor) is provided is widely used for an active-matrix liquid crystal display, an organic EL (Electro-Luminescence) display, or the like. Those displays are increasingly large-sized along with development of high-definition television broadcast. Mother glasses used to manufacture those panels are also increasingly large-sized year by year. Currently, the glasses are manufactured in size of 2880 mm×3130 mm, which is called the tenth generation.
On the other hand, an interposer substrate used for a package of an IC (Integrated Circuit) is started to be commercially practical as a package form of a high-performance IC, because microfabrication of wirings, which has reached a deadlock for an organic resin substrate, can be carried out by using Si (Silicon) substrate.
However, the interposer substrate made of a Si substrate is expensive, which is disincentive to develop the substrate with respect to other IC packages except some high-end products. Under the circumstances, expectations have raised for use of a “large-sized glass substrate that allows fine wirings” as the interposer substrate, which can be more inexpensive by increasing the number of extractions.
Behind the expectations, there is the fact that a technology for processing vias in a glass substrate has been developed, for example. To use a glass substrate for the interposer, through glass vias (TGVs) that penetrate the substrate to connect wirings between a front surface and a back surface are necessary. For this reason, a practical processing technology is demanded which makes it possible to form a great number of fine vias in a glass substrate at a low cost. As a technology in related art for forming fine holes in glass, abrasion by using laser is known. However, for an interposer use in which a great number of vias are necessary, it is almost impossible to achieve practical manufacture thereof due to a processing time period and a total thereof by sequential processes. In recent years, as a technology instead thereof, a via opening technology by using electrical discharge machining or photosensitive glass has been developed.
An example of the via opening technology includes a machining method such as focused electrical discharging. By the focused electrical discharging, it is possible to form vias in a glass substrate in a short time of 1 msec/via (see, 45th International Symposium on Microelectronics (IMAPS 2012), Proceedings, TP13, 2012). In the machining method, after the vias are formed, it is necessary perform a heat treatment at approximately a softening point of glass in order to relieve a stress on opening portions.
Further, as another via opening technology, a technology for forming vias by using photosensitive glass has been developed (see, NEW GLASS, p. 75-80, Vol. 22, No. 1, 2007, and 45th International Symposium on Microelectronics (IMAPS 2012), Proceedings, TP12, 2012).